If you don't mind I'm going to focus on the 9 receptions on 3rd down along with the 8 first downs gained, rather than than break down the 2 sacks.

Dave Hyde wrote:

If you singled out where Ryan Tannehill excelled against the Browns, it was third down. And this was added evidence to why there’s big hope for him to take a significant stride forward this year.

In his rookie year, Tannehill struggled on third down as shown by his 65.3 rating (59 completion pct, 3 TDs, 7 Int). You can break it down further. On third downs of less than six yards, he had a 73.7 rating (56 pct, 2 TDs, 2 int, 5 sacks). On third downs of more than six years, he had a 60.9 rating (60.6 comp., 1 TD, 5 int, 6 sacks).

Against Cleveland, Tannehill was much improved on third down. It’s just one game. But if this one game is the result of a quarterback’s maturation (and better receiving cast) and not just a random day, it bodes well for this season. He completed nine of 13 passes for 82 yards on third down and what his 86.1 rating doesn’t fully bring out is eight of them went for first downs. A ninth would have come on his initial third-down pass that Brandon Gibson dropped over the middle. (On the negative, he was sacked twice on third downs in the second quarter.)

On third downs of less than six yards, Tannehill completed five of six passes - and the Gibson drop was the sole incompletion. All five of the completions went for first downs. On yet another third-and-five, Cleveland’s Paul Kruger jumped offsides. So on the seven times the Dolphins had third down and less than six yards and threw (or planned to, as a pass was called when Kruger jumped offsides, Tannehill got six first downs and was a drop from being a perfect seven-for-seven.